The mitral valve exhibits two types of pathologies regurgitation and stenosis. Regurgitation is the more common of the two defects. Either defect may be treated by surgical repair. Under certain conditions, the mitral valve must be replaced. Standard approaches to mitral valve replacement require cutting open the left side of the heart to access the native mitral valve.
US 2008/0071368 to Tuval describes a prosthesis for implantation at a native semilunar valve of a native valve complex. The prosthesis includes a distal fixation member, configured to be positioned in a downstream artery, and shaped so as to define exactly three proximal engagement arms that are configured to be positioned at least partially within respective ones of semilunar sinuses, and, in combination, to apply, to tissue that defines the semilunar sinuses, a first axial force directed toward a ventricle. The prosthesis further includes a proximal fixation member coupled to the distal fixation member, the proximal fixation member configured to be positioned at least partially on a ventricular side of the native semilunar valve, and to apply, to the ventricular side of the native valve complex, a second axial force directed toward the downstream artery, such that application of the first and second forces couples the prosthesis to the native valve complex.
US 2009/0276040 to Rowe describes a prosthetic mitral valve assembly and method of inserting the same. In certain embodiments, the prosthetic mitral valve assembly has a flared upper end and a tapered portion to fit the contours of the native mitral valve. The prosthetic mitral valve assembly can include a stent or outer support frame with a valve mounted therein. The assembly is described as being adapted to expand radially outwardly and into contact with the native tissue to create a pressure fit. One embodiment is described including positioning the mitral valve assembly below the annulus such that the annulus itself can restrict the assembly from moving in an upward direction towards the left atrium. The mitral valve assembly is also described as being positioned so that the leaflets of the mitral valve hold the assembly to prevent downward movement of the assembly towards the left ventricle.
US 2010/0217382 to Chau describes a prosthetic mitral valve assembly and method of inserting the same. In certain embodiments, the prosthetic mitral valve assembly includes a stent and valve combination. The stent is designed so that the anchoring portion is positioned above the annulus of the mitral valve and in the left atrium. The stent is radially expandable so that it can expand into position against the walls of the left atrium and accommodate a wide range of anatomies. Contact between the stent and the native tissue in the left atrium is described as reducing paravalvular leakage and preventing migration of the stent once in place.
US 2009/0005863 to Goetz describes a replacement valve for implantation centrally within the orifice of a malfunctioning native heart valve. The valve is designed for minimally invasive entry through an intercostal opening in the chest of a patient and an opening in the apex of the human heart. The replacement valve includes either a separate anchor or a combined anchor that folds around the malfunctioning native valve leaflets, sandwiching them in a manner so as to securely anchor the replacement valve in a precise, desired location.
US 2009/0216312 to Straubinger describes a stent for the positioning and anchoring of a valvular prosthesis in an implantation site in the heart of a patient. Specifically, the Straubinger application relates to an expandable stent for an endoprosthesis used in the treatment of a narrowing of a cardiac valve and/or a cardiac valve insufficiency. The stent is described as comprising at least one fastening portion via which the valvular prosthesis is connectable to the stent, so as to ensure that no longitudinal displacement of a valvular prosthesis fastened to a stent will occur relative the stent in the implanted state of the stent, even given the peristaltic motion of the heart. The stent further comprises positioning arches and retaining arches, whereby at least one positioning arch is connected to at least one retaining arch via a first connecting web. The stent moreover comprises at least one auxiliary retaining arch which connects the respective arms of the at least one retaining arch connected to the at least one positioning arch.
US 2008/0255660 to Guyenot describes a medical device for treating a heart valve insufficiency, with an endoprosthesis which can be introduced into a patient's body and expanded to secure a heart valve prosthesis in the patient's aorta. In an embodiment, the endoprosthesis has a plurality of positioning arches configured to be positioned with respect to a patient's aorta and a plurality of retaining arches to support a heart valve prosthesis. The endoprosthesis includes a first collapsed mode during the process of introducing it into the patient's body and a second expanded mode when it is implanted.
The following references may be of interest    US 2010/0030330 to Bobo    US 2009/0216313 to Straubinger    US 2009/0216310 to Straubinger    US 2008/0255661 to Straubinger    US 2008/0208328 to Antocci    US 2008/0071369 to Tuval    US 2008/0071363 to Tuval    US 2008/0071366 to Tuval    US 2008/0071362 to Tuval    US 2008/0071361 to Tuval    US 2003/0036791 to Bonhoeffer    WO 04/019825 to Figulla